To investigate the effect of nutritional condition of the honey bee Apis mellifera on the development of the microsporidian parasite Nosema ceranae under laboratory conditions, newly emerged bees were confined and fed on three adlibitum diets: high fructose corn syrup (HFCS) + fresh bee bread; HFCS + a commercial mixture of amino acid and vitamin, and HFCS. On day 7 post-emergence, bees from each diet treatment were individually infected with 4.60 x 104, 2.30 x 105 or 1.15 x 106 spores of N. ceranae, keeping later on the same diet. On days 3, 6, 9, and 12, post-infection bee midguts were removed to individually quantify the spores developed. The results indicate that this parasite multiplies successfully regardless of the inoculum given or the nutritional status of its host. When bees are fed on pollen, however, the parasite develops quickly, exhibiting significantly higher intensities than under other treatments. The longevity of infected bees fed on the same diet was not affected by the degree of parasitism, but by the quality of the ad libitum diet administered. The data demonstrate a parasite development that depends on host-condition. This should be considered when designing experiments to evaluate the development and virulence of this pathogen.

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